   "Connect N controls of a node to a set of sequential control busses,
   starting at the given control name."
   [node start-control start-bus n]
-  {:pre [(server-connected?)]}
+  (ensure-connected!)
   (assert (bus? start-bus) "Invalid start-bus")
   (let [node-id (to-synth-id node)]
     (snd "/n_mapn" node-id (first (stringify [start-control])) (bus-id start-bus) n)))


  {:freq 440.0 :attack 0.2}"
  [node names]
  (let [res (recv "/n_set")
        _ (apply snd "/s_get" (to-synth-id node) (stringify names))
        cvals (:args (deref! res))]

(defn- group-clear*
  "Free all child synth nodes in a group."
  [group]
  (ensure-connected!)
  (snd "/g_freeAll" (to-synth-id group))
  :clear)

